


Something I Can Never Have

by coldrottingtrees



Category: Supernatural
Genre: Anal Fingering, Anal Sex, Angst, Barebacking, Begging, Bottom Dean, Cock Warming, Coming Untouched, Depressed Dean, Dubious Consent, Emotional Manipulation, Incubus Castiel, Light Dom/sub, M/M, Mind Control, Oral Sex, Rough Sex, Season/Series 09, Sirens, Sleep Sex, Succubi & Incubi, Top Castiel, sextoy!Dean
Language: English
Status: Completed
Published: 2014-03-06
Updated: 2014-03-07
Packaged: 2018-01-14 17:38:30
Rating: Explicit
Warnings: Rape/Non-Con
Chapters: 3
Words: 5,437
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/1275148
Author URL: https://archiveofourown.org/users/coldrottingtrees/pseuds/coldrottingtrees
Summary: <blockquote class="userstuff">
              <p>fill for the spn kink meme.</p><p><a href="http://spnkink-meme.livejournal.com/83218.html?thread=31065106#t31065106">Original prompt</a>:</p><p>"certain sirens capture and care for a single victim for decades before the victim dies and the siren moves on. And since sirens turn into someone's "heart's desire," Dean probably should have been prepared to find Cas down there (but he wasn't).</p><p>Obviously, it wasn't Cas, but Dean clued into that one around the time it was making out with him - which is to say, quite a bit too late; he didn't care anymore...</p><p>I am 100% fine with the siren successfully getting away with Dean indefinitely/forever; I am also up for Sam-and-Cas finding Dean getting fucked into the mattress by the siren (still looking like Cas) and managing to kill the siren (without seriously injuring Dean). If the latter route, Dean should fight tooth and nail to stay with who he knows and doesn't care is the siren (until it's dead); either way, I'd like Dean being fucked a lot & pretty much worshipping the siren (and mostly begging it to fuck him)."</p><p>Title is from a Nine Inch Nails song. <a href="http://www.azlyrics.com/lyrics/nineinchnails/somethingicanneverhave.html">[Lyrics]</a></p>
            </blockquote>





	1. Chapter 1

**Author's Note:**

> I basically just took the beginning of episode 9x15 and changed it so Dean left without Sam instead of letting him come along. And obviously it's leaving for a different case. So yeah, in case it looks like I just blatantly ripped off the show, yes. Yes I did. I'm lazy.

“Where’re you headed?”

Dean turned to look at Sam, keys in one hand, duffel in the other. “Got a case.”

“And you’re just going by yourself?”

“Easy one, I’ve got it handled,” Dean said, trying to sound casual and detached. But he could hear himself as he spoke, and internally winced at how defensive and wounded he sounded.

“I’m not doing anything, I could come with you,” Sam pointed out irritably.

“Yeah, let’s not,” Dean bit out. “We need some space, right?”

 _STOP sounding like such a dumped boyfriend,_ Dean cursed at himself. He just couldn’t seem to rein it in, which is why he needed to get the fuck out of the bunker and away from Sam. He was _pining_ , and it was humiliating.

“Have it your way, Dean,” Sam said, shaking his head angrily, turning his eyes back to his books.

Dean nodded and continued on his way to the garage.

It really was an easy case. Seemed like a pretty obvious siren issue, and Dean (unfortunately) already had experience with those. And quite honestly, the last time he’d tackled a siren, having Sam there had made it so, so weird. Even if they weren’t currently fighting, he probably wouldn’t have wanted to risk a repeat of _that_ clusterfuck.

Dean tossed his duffel into the trunk of the impala and hauled ass for the interstate, eager to put some physical distance between himself and Sam.

* * *

Day One of the siren hunt turned up nothing. Dean celebrated his failure by hitting a local bar to see how his alcohol tolerance was doing these days.

Three beers in and he was considering violating the beer before liquor rule. Beer just wasn’t cutting it. What he really wanted was whiskey, and he was irritated that he hadn’t just started off with it.

“Dean?”

Dean’s eyes shot up toward the voice, his fingers falling away from the beer label he’d been picking at.

“Cas?” he murmured, incredulous.

Cas smiled and sat down at the table with him.

“What the hell’re you doing here?”

Cas spread his hands and shrugged. “Same as you, hunting.”

Dean laughed softly and shook his head. “You just don’t quit, do you? I thought I told you to give it a rest with the hunting thing.”

“I learned from the best,” Cas said sincerely. “Why would I put those skills to waste?”

Dean huffed, lowering his eyes back to his empty beer bottle.

“Dean,” Cas said seriously, lowering his voice.

Dean looked up, meeting his eyes.

“Can we speak somewhere more private? You and I… we have much to discuss.”

Dean swallowed nervously. He’d had about enough of serious talks.

“Sure, Cas,” he eventually said. He owed Cas, whether he looked forward to it or not.

“Do you have a motel room here in town? We can go there.”

“Yeah, sure,” Dean said, getting up from the table. Cas got up with him, and Dean couldn’t help a quick, appreciative up and down. “I’m glad to see you,” Dean admitted, looking away.

Cas smiled. “I know.”

* * *

“Ugh, monkey suit,” Dean grumbled, quickly shrugging out of his jacket as they walked into the motel room. “So, let’s hear it,” he said, turning to face Cas, loosening his tie.

Cas _eyed_ him. Dean’s face heated up instantly, and his fingers fumbled in their attempt at undoing the button at his collar. There was no mistaking it, not at all. Cas’s eyes slowly worked their way down Dean’s body and just as indulgently made their way back up.

“Um,” Dean stuttered.

He didn’t have time to come up with something to say before Cas closed the space between them, grabbed him by his loosened tie, and hauled him forcefully up against his body.

Dean’s breath hitched and he stared into Cas’s eyes, overwhelmed.

Hand still fisted around Dean’s tie, Cas kissed him. This was not the hesitant, inexperienced Cas he’d envisioned in the many (deeply secret) times he’d imagined what this moment would be like. Cas sucked Dean’s lower lip between his teeth and gave it a bite just hard enough to send electricity jolting from Dean’s lips all the way through him. Cas shoved his tongue past Dean’s lips, stroking Dean’s tongue, fucking his mouth. He kissed like a sex god; he had Dean on fire in seconds.

Dean shucked the raggedy trenchcoat he loved so much off Cas’s shoulders and then the black jacket, leaving them both in matching button-down shirts and ties.

“Get on the bed,” Cas ordered, voice low and rough. Every word went straight to Dean’s dick.

He obediently went to the bed and sat on the edge. He stared at Cas, stupefied with shock.

Cas came up to Dean and removed his tie - unknotting it and then sliding it from his collar in a way that made Dean shiver. He gazed up at Cas, awed. Cas unbuttoned Dean’s shirt slowly, and Dean basked in his nearness and the soft sensation of his nimble fingers through the cloth.

“Cas, I…” Dean began falteringly. “I didn’t think you…”

Cas pulled the ends of Dean’s open shirt out of his pants and then pushed it off his shoulders. Dean’s naked skin prickled at the air conditioned coolness of the room.

Something itched at the back of Dean’s mind. He felt like he was missing something important.

Cas kicked open Dean’s legs and knelt between them, and all thoughts were blown blissfully away. Cas opened his fly and ordered Dean to stand just long enough to drop the pants and his underwear to the floor. Dean sat back down, Cas between his knees, and watched in wide-eyed wonder as Cas took his already hard cock in hand and ran his beautiful, long pink tongue from the base all the way to the tip.

Dean shivered and gripped the edge of the bed so hard the tips of his fingers ached from the pressure.

Cas swirled his tongue around the head of Dean’s cock, lapped at the underside kitten-like, and then sucked it fully into his mouth.

Dean thought he might die of rapture. His hips rocked up toward Cas before he could get the presence of mind to stop himself. His whole body craved as much contact with Cas as he could possibly get, but he didn’t want to gag him, so he willed his hips still.

Dean moaned weakly, shuddering with pleasure, and Cas hummed approvingly. _That voice_ reverberated through his cock, and Dean gasped, his hips flexing toward Cas again.

Cas sank down on Dean’s cock, lower and lower, until Dean could feel his cock sliding down Cas’s throat.

“Oh… fuck….” Dean whispered shakily.

Cas worked Dean’s cock with his mouth and hands until Dean was a quivering mess right on the edge of orgasm.

“Cas, Cas I’m close,” Dean panted warningly, and Cas pulled away. Dean groaned pitifully, letting his head fall back.

“Don’t worry,” Cas said, voice graveled, “I’ll make you come. But I want to fuck you first.”

Dean lifted his head to stare at Cas. “You… you what?”

“I know you keep lubricant in your travel bag,” Cas said. “May I use it?”

All Dean could do was nod. He watched Cas go to his duffel and dig around until he found the bottle of lube. He knew he should mention the condoms but he just… didn’t. He felt reckless, he didn’t care about anything at all anymore, and he really wanted to feel Cas coming.

Cas took the lube and set it on the nightstand, and then came back to stand in front of Dean.

“Get on your knees,” he said, pointing at the floor at his feet.

Dean didn’t think, didn’t question, just obeyed.

“Get me hard,” Cas said.

Dean opened Cas’s fly and pulled down his pants and boxers. He took a moment to just admire Cas’s cock - thick and a nice length even semi-soft, nestled in pubic hair darker than Dean’s own - and before he could freak himself out over-thinking the fact that this was irrefutably, definitely gay, grabbed it and sucked the head into his mouth.

Cas sighed with pleasure and ran his fingers through Dean’s hair. Dean loved having his hair touched, and that small act alone made him actively concentrate on making his mouth as sweet as possible for Cas, trying to thank him for the touch.

“Mm, that’s enough, don’t want to come yet,” Cas said gently, voice ragged with lust. He pulled away from Dean, and Dean found himself, to his utter shock, disappointed.

Enjoying sucking cock? Enjoying it a _lot?_ Really?

“Get on the bed, on your stomach,” Cas said, taking off his tie.

“Yes, sir,” Dean heard himself automatically say.

Cas didn’t embarrass him by reacting to it. He seemed to just find it natural, normal. Dean got on the bed and laid down.

Dean was reminded that his somewhat comically inept friend had also been a captain of an entire garrison of angels. It was the captain in his voice now, the proud soldier of the Lord, and it made Dean’s dick hard. It brought out the part of him that had always been forefront around his father, the side that followed orders. Needed them.

Face turned to the side on a pillow, Dean felt the bed dip as Cas climbed on. He pushed Dean’s legs further apart and knelt between them. Dean clutched the pillow tight, getting nervous, as he heard the click of the lube cap being popped.

“You done this before?” Dean asked. “With a guy?”

“I’ve done many things in your absence,” Cas said.

Dean wasn’t even jealous, not really. He found himself grinding his hips slightly into the bed, thinking about Cas fucking as many guys as he could get his hands on. Dean had always had a thing for experience.

“Don’t worry,” Cas assured him. “I know how to make this good for you.”

Dean felt a lubed finger slide against his hole, the lube not as cool as he’d feared it would be. His hips rocked, rubbing his cock against the mattress.

“You’re mine, aren’t you?” Cas purred, slowly working a finger inside.

Dean moaned, the sensation sending ripples of pleasure through his body. He lifted his hips, wanting more.

“Say it,” Cas insisted.

That something was scratching at the back of Dean’s mind again. Something… something very important. He was forgetting something very important.

Another finger slid, lube-slick and perfect, inside. Cas worked his fingers in and out, deeper and deeper, until he could slide his fingers smoothly all the way to the last knuckle.

“Say you’re mine,” Cas said, pulling his fingers out, leaving Dean empty.

Dean groaned pitifully, wanting Cas back inside. Wanting Cas back.

 _Cas lost that trenchcoat,_ Dean thought. _Hasn’t had it since he fell…_

“Say the words and I’ll give you what you want, Dean,” Cas whispered, crouched over his body, lips against his ear.

He wasn’t sure if he’d been ignorant or willfully blind, but he was sure of it now. He had a choice to make, he could either do the job he’d come here to do, or…

Maybe…

Maybe he could have this one perfect thing, just one, just one sweet, beautiful thing, and maybe even die happy.

“I’m yours,” Dean whispered, closing his eyes.

“I love you, Dean,” Cas said softly, lining his cock up against Dean’s entrance. “I need you.”

“I need you, too,” Dean breathed, voice broken.

Cas slowly pushed his cock inside and Dean moaned at how good it was. He wanted more, he wanted this over and over, he wanted this forever.

Cas rocked in and out shallowly, warming Dean up, getting him used to the size and the stretch, and once Dean had relaxed into it enough, he pushed, sliding in as deep as he could get. Dean arched his hips up toward Cas’s body, wanting all of it.

“Going to make this good for you, Dean,” Cas said into his ear, that rough voice so good against the sensitive skin.

“Please,” Dean begged.

Cas fucked him hard and fast, shoving his face against the pillow. Dean gasped and moaned out loud, clenching his fists in the blankets. He panted and cursed and called out, writhing between Cas’s body and the mattress, his mind wiped clean of all the ugliness and doubt and despair, nothing but white hot pleasure and desire.

“I’m yours,” Dean swore.

Cas moaned and shuddered and then he was coming, and Dean could feel Cas’s cock pulsing inside him with the intensity of his orgasm and it was perfect. It was everything he wanted. His vision whited out and his body trembled as he came without even touching his cock.

“You’re so perfect,” Cas said, kissing up Dean’s spine. “I’ll never let you go.”

“Promise me,” Dean said breathlessly, eyes closed, focusing on the sensation of Cas’s lips against his skin.

“I promise,” Cas answered.

**Notes for the Chapter:**

> here, have a nice [visual for this chapter](http://mrsfitzgerald.tumblr.com/post/75719447025) SFW (not my blog)


	2. Chapter 2

Sam’s phone rang, and Sam scrabbled frantically at his pocket to get it out and answer it as fast as he could. His heart sank when he didn’t recognize the number.

“Hello?”

“Sam. Are you and your brother okay?”

“Cas,” Sam sighed. “Good to hear from you. I’m… fine. Not sure about Dean.”

“What do you mean?”

“He’s… been gone for a while. I’m not sure where he’s at and he hasn’t answered any of my calls or texts.”

“He didn’t answer my calls, either.”

“Why’ve you been trying to reach him? Everything okay?”

“I was concerned. I haven’t heard from him in some time.”

“When’s the last time you heard from him?” Sam asked.

“Fifteen days, eighteen hours, and twelve minutes ago.”

“Oh,” Sam said, a little astonished at the specificity. He then visualized a calendar, trying to figure out what day of the week that would be. “I think that was around when I saw him last, actually, give or take, you know, some minutes or hours.”

“I’m very concerned,” Cas reiterated, voice grave.

“Is it really that weird for him to go without calling you for a while?” Sam asked, surprised.

“He seldom calls my phone. But he prays, sometimes every day. The absence is very noticeable.”

Sam scoffed, surprised. “He always claimed he wasn’t religious.”

“He has faith in certain things,” was Cas’s only reply.

“Can you tell where he is?”

“No,” Cas said regretfully. “The spell I engraved on your ribs still prevents me from locating either of you through conventional means.”

“How fast can you get to the bunker? I’m gonna do some research, try to figure out where he might’ve gone. I could use some backup when I go looking for him.”

“I’ll be there as quickly as I can.”

* * *

 

Dean lay draped over Cas, pressing worshipful kisses along his stubbled jaw, atop his beautiful cheekbones, to his temples and very softly on each eyelid, delighting in the feel of Cas’s long eyelashes against his lips. Cas ran his hands down Dean’s back and back up his sides, lingering over the newly prominent ridges of his ribcage.

“You should eat more,” Cas said. “Keep up your strength.”

“I feel like I’m already eating you out of house and home,” Dean chuckled.

“I don’t need food; I don’t need anything. Everything I have is yours. All I need is you.”

“Sappy,” Dean said with an eyeroll. But internally he ate up every word, cherished them. He ran his kisses down Cas’s neck, up along his ear, trying to make his true feelings understood the only way he knew how.

Cas sighed as Dean nibbled and licked his ear, digging his fingers into Dean’s back.

“You like that, Cas?” Dean whispered into his ear, voice low and breathy so Cas could feel it.

“You’re perfect,” Cas answered, raking his fingers down to grab Dean’s ass. “I love you. I never want to lose you.”

“I’m not going anywhere,” Dean promised. He ground his hips against Cas, the way Cas reacted to having his ears played with making him hard. “I want… I want you,” he said quietly.

“Tell me what you want,” Cas ordered. “Say it.”

Dean whined low in his throat. The words were still so hard. He pushed himself down Cas’s body and dropped his mouth to Cas’s nipple, kissing and stroking and lapping at it with his tongue. It was so much easier, using his mouth this way than speaking with it.

Cas groaned with pleasure and arched his body up toward Dean, running his fingers through Dean’s hair.

“I want to hear you say it,” Cas said, voice husky.

Dean closed his eyes, cocking his head toward the hand Cas pushed through his hair appreciatively.

“I want you to fuck me,” he whispered.

“Open your eyes,” Cas said. “Look me in the eyes and say it loud enough I can hear you.”

It had been two weeks since he and Cas had started fucking. Cas had brought him back to the house he had now ( _Cas doesn’t have a house,_ a voice had whispered in Dean’s mind, a voice he ignored), and Dean had barely left the bedroom at all this whole time. There were days he woke up in the morning to Cas already fucking him, and fell asleep that night with Cas’s soft cock still inside, resting inside him. He couldn’t get enough of Cas; he felt like they had years of wasted time to make up for… and he felt like there wasn’t nearly enough time left to do it in. He wanted as much as he could get; he wanted to drown himself so completely in it that everything that came before, the pain, the horrible mistakes, the fear, the cruelty, the abuse, would all feel far away and _over_. He wanted to be able to say that at least all that awfulness culminated in getting the chance to love Cas, getting to eventually be _happy_.

Two weeks of frantic, nearly non-stop fucking, hell, _love-making_ , and Dean somehow still found it difficult to just come right out and ask for it.

Cas pulled him back up close and kissed him. Dean’s desire became increasingly urgent under Cas’s skilled lips and tongue. His breath stuttered and his cock slid against Cas’s hip, the head wet with pre-come.

“Say it,” Cas whispered against Dean’s lips.

“Fuck me,” Dean said hoarsely.

Cas reached down and gripped Dean’s cock, making Dean whimper out-loud.

“What, Dean?”

Dean opened his eyes to meet Cas’s. “Please, fuck me,” he begged.

Cas smiled and gave Dean’s cock a few rewarding strokes.

“Please,” Dean begged. “Please, Cas. I want it bad.”

“Get on your hands and knees,” Cas ordered.

Dean complied gratefully. Cas got out of bed and grabbed Dean to pull him into place at the edge. He lubed up his cock with the bottle on the nightstand and didn’t bother prepping Dean at all. Dean was still slick with lube and come from the last time they’d fucked not long ago. He grabbed Dean’s hip and guided his cock inside in one long, smooth push, burying himself fully. Both hands gripping Dean’s hips roughly, he started pounding into him, fucking him so hard it made Dean see stars.

“Oh, fuck… Cas, yes…” Dean panted, fingers clenched in the sheets, cock hard and leaking.

“Make yourself come,” Cas said, pounding Dean so hard Dean would have bruises from Cas’s fingers digging into his hips, slamming them back onto Cas’s cock with each forward thrust. “Want to feel you come on my cock.”

Dean took his cock in hand and started stroking. His whole body started trembling, already close. He closed his eyes, overwhelmed, thoughts gone, mind an empty black canvas on which fireworks of pleasure bloomed. It was as close to serenity as he’d ever gotten.

Dean’s orgasm hit him so hard he yelled, an inarticulate burst punched from his gut. Cas moaned, fucking Dean through it, until he too was coming, filling Dean even more full of his come.

They both collapsed back onto the bed, sweaty and messy and deliriously happy. Cas petted Dean’s hair, and it was so perfect, felt so good, so warm and safe, that Dean briefly dozed off.

* * *

“Ugh, damn, it’s definitely shower time,” Dean said, peeling himself away from Cas.

Cas smiled and nodded with a little hum of assent.

“Gimme a minute to use the john, then come join me,” Dean said, and walked off to the bathroom.

When Cas came in, Dean was looking at himself in the mirror. He looked gaunt. He had dark, sunken circles under his eyes and his skin was deathly pale.

“You should eat more,” Cas fretted, coming up behind Dean and looking at Dean’s reflection as well. “Tell me what you want, anything, I’ll get it for you.”

Dean saw the worried look on Cas’s face reflected in the mirror beside him.

 _Sirens show their true form in reflections…_ Dean thought, but he was so weak it was difficult to hold a train of thought.

“I can come with y--” he began, and then passed out.


	3. Chapter 3

Sam stood just inside Dean’s room, stuck in place like a bug in a glue trap. He looked all around, his eyes finding and lingering on every item Dean owned.

 _What if he’s dead?_ a voice whispered in Sam’s head. _What if this is all that’s left of your big brother now, just a cold empty room…_

Sam had already lost his brother before. So many times he’d actually lost count. There was a place in Sam’s heart that had gone numb, a coldness that never thawed even when Dean inevitably came back. He was always glad to have his brother back, and he would always love him, desperately love him, but after a certain amount of shock, a certain amount of torture, there were places that just shut off inside a person, and no relief, no coming back, could turn that piece back on again.

Dean didn’t understand that. Dean expected Sam to just go back to being the same smiling kid he’d left, because _Hey, I’m back now!_

But it just didn’t work that way. Pain was pain, whether the source was permanent or not, and pain changes people.

Sam walked across the room and reached up to touch one of the guns mounted on the wall. It was dusty. He wondered if Dean even knew to dust. People who lived in cars and motel rooms didn’t need to dust.

He’d been so excited to have a room. He’d wanted to put down roots. Despite his angry assertions otherwise, Sam was fairly sure Dean wanted to settle down.

Sam looked at the neatly made bed. Sam himself had never mastered the art of making a bed. John had certainly never taught him. Amelia had tried to teach him how to make a bed, and he understood the general premise, make the sheets lay smooth and even. But when he tried, it always came out lumpy and crooked, and mostly, Sam didn’t even see the point.

Sam wondered if their mother had taught Dean how to do it.

Sam saw Dean’s laptop still sitting on his desk and pulled the chair over. When he opened it, it prompted for a password, and, thanks to Dean being the most highly predictable person ever, Sam was able to guess it on the third try.

Dean’s browser was still up, and, helpfully, all his tabs were still open. Sam carefully avoided anything that looked like it might be porn, and checked the rest - news articles, research pages, Google maps, and, surprisingly, some recent coroner’s reports.

“First you’re hacking security cameras and now you know how to access medical records?” Sam murmured to the brother who wasn’t there. “I’m impressed, Dean.”

The coroner’s reports all mentioned abnormally high levels of oxytocin, and Dean’s research focused on sirens.

“Dean, wait,” Sam said, going back to the autopsies. “This doesn’t match pattern. Sirens make the person under their thrall kill someone they love, the murder vics won’t be the ones with the oxytocin in their system.” Sam pulled up pictures of the corpses. “These people, they look… drained.”

 

* * *

 

“So, here’s what I know,” Sam said, driving through Peoria, Illinois on War Memorial Drive. “He probably stopped at St. Francis Hospital to talk to the coroner. He probably picked Baymont motel here on War Memorial since it’s right off the interstate and it’s the first one in the phonebook--”

“Wait, Sam, turn here,” Cas said suddenly, pointing to turn left at University.

Sam immediately did as told, desperately eager for any lead at all. “What is it, Cas?”

“Now, turn,” Cas said, gesturing to take a right on Lake. “I can’t locate you or your brother anymore, but…”

Cas went silent, his eyes scanning. “Here, turn in here.”

Sam turned into a shopping plaza. Cas had him turn down one of the lanes of the parking lot and then Sam saw it, too.

Baby.

Sam parked nearby, close enough to watch but hopefully not be seen.

“A grocery store?” Sam muttered. “No contact in two weeks, and he’s just doing some light shopping?”

Cas frowned and said nothing.

“Hey, Cas,” Sam eventually said.

“Yes?”

“Is there any way… I mean… if Dean died. Would you be able to find out, and tell me?”

“Your brother is not dead.”

“Are you sure?”

“Yes,” Cas said firmly, eyes still set on the Impala.

Sam nodded.

They spent the next twenty minutes in silence, watching shoppers coming and going, until Sam spotted a very familiar trenchcoat. Sam watched in shock as a man who looked exactly like Cas, wearing all of Cas’s old clothes, pushed a shopping cart filled with bags down the lane and stopped at the Impala.

Sam looked at Cas, briefly horrified that he hadn’t even questioned whether the man he’d invited into the bunker was actually the real Castiel.

Cas, meanwhile, was staring holes into the look-alike. He looked more murderous than Sam had ever seen him.

“That creature has Dean,” he growled. “We have to follow it back to where it’s keeping him.”

“Cas, mind if I check something?” Sam asked, and removed a small flask from his coat pocket. Without waiting for a response, he splashed holy water mixed with Borax onto Cas’s hand. Nothing happened.

“Of course, here,” Cas said, pulling his now sodden coat sleeve up to expose his forearm. Sam took out a silver dagger and nicked Cas’s arm.

“Thanks,” Sam said, relieved.

Cas nodded, the cut on his arm healing closed.

“Dean would never let something drive his car,” Sam whispered, watching the Cas copy load his groceries into the back seat. “You’re absolutely sure Dean’s not dead?”

The last thing the creature took from the cart was a pie box. Sam watched as he gingerly put the pie in the passenger seat, separate from the rest, presumably to make sure it didn’t get crushed by shifting groceries while driving.

“Okay, maybe it is keeping Dean alive. Kind of nice, for a monster.”

Cas said nothing, only stared, radiating malice.

Other Cas responsibly returned his shopping cart to a cart corral, got into the Impala, and drove away.

Sam tailed him.

* * *

Cas set the last of his bags of groceries down on the kitchen table and then went to the bedroom, looking for Dean.

“Dean?” he called, coming into the room. “I brought you orange juice, and the things you need for making hamburgers…”

Dean lay in the bed, his breath coming in shallow rasps. He was fully dressed and had blankets pulled tightly to his chin. His body didn’t even have the energy to keep itself adequately warm anymore.

Cas stroked his face gently, worry in his eyes. “I got you pie, as well. It’s cherry, I think you enjoy that one.”

Dean smiled. “Thanks, Cas.”

“Come to the kitchen, I’ll feed you anything you like. If you don’t want burgers, I brought chicken noodle soup. I believe humans in this area enjoy it when they feel ill.”

Dean sat up slowly, and Cas tucked an arm under Dean’s and around his back to help him the rest of the way up. Just as they neared the doorway, Cas stopped, holding out an arm to keep Dean behind him.

“Someone’s here,” he whispered, listening intently and scenting the air.

Cas stepped into the doorway, peering out toward the living room, and was suddenly blown back by an invisible force, slamming into the opposite wall and crumpling to the floor.

“Cas!” Dean shouted, but his knees buckled when he attempted to run to Cas’s side.

He looked up and saw _Cas_ walk through the door. Cas’s eyes burned angelic blue, pinned to the other Cas across the room, and his every inch radiated heavenly wrath. Sam followed close behind, Ruby’s knife in hand.

“No! Cas, stop!” Dean cried out, dragging himself toward what he knew was a monster, trying to protect it.

The real Cas looked at him as though he hadn’t even noticed him there yet, so intense was the focus of his rage. His eyes softened with concern, and he stopped Dean in place with fingers lightly touched to his forehead.

Dean gasped as he felt himself restored. He looked up at Cas and watched the blue light in Cas’s eyes flicker out, the energy it took to heal Dean seeming to take a lot out of him. Dean got to his feet.

“This is an abomination,” Cas said, pointing at the Cas against the wall on the floor.

Dean stepped between this Cas and that one. “I don’t care. I won’t let you hurt him.”

“Dean, it’s a succubus,” Sam shouted. “Er, incubus maybe, whatever. It’s a _demon_. Get out of the way and let us kill this thing.”

 _Oh_ , Dean thought, looking back at the Cas against the wall. _So that’s what you are._

“Help me,” the incubus with Cas’s face pleaded.

The compulsion hit him like a freight train. He would protect this creature no matter the cost. His eyes skipped back and forth from Sam to Castiel, trying to figure out how to take them both out at the same time. If he could just immobilize Castiel for a moment somehow, he could take out Sam, get the knife, and use the knife to draw some blood to make a banishing symbol…

But in that split second, while Dean’s mind raced attempting to strategize, Castiel let out a snarl of rage at the incubus’s command. His eyes glowed blue again, and a high-pitched whine filled the air, so loud it made Dean and Sam both instantly cover their ears and wince.

Through the hands over his ears, Dean could hear a sound like a chorus of voices whispering at once, and the soft rustling of a thousand feathers combing the air.

“Dean Winchester is protected,” Castiel thundered.

Dean was swept away by an invisible force that felt suspiciously like an enormous wing. He was knocked to the floor, and could only watch as Castiel struck a hand to the incubus’s forehead.

The incubus screamed, its voice horribly inhuman, as light erupted from its eyes and mouth, incinerating it from the inside.

Castiel removed his hand, and the incubus fell to its side on the floor.

Dean blinked, his head slowly clearing. He watched as the incubus’s countenance dissolved from Cas’s face to something shriveled and grey and hairless. He felt revolted, imagining that thing touching him.

Cas, the real Cas, stepped over to Dean and helped him up from the floor. He studied Dean’s eyes, as if trying to measure whether Dean was alright.

“You were very close to death,” Cas said quietly. “It was devouring you.”

“I’ll be out in the car,” Sam said, and left.

Dean watched Sam go, and then turned back to Cas. “Thanks,” he murmured. “For saving me.”

Cas nodded once.

Maybe it was the lingering effect of the incubus. Maybe it was just finally being sick of wanting something so much, something that was _right there_ , and never having it. Maybe his eyes were just finally open. What he wanted wasn’t the wolf in sheep’s clothing smoking on the floor, it was the blue eyed angel of the Lord standing right in front of him.

Dean closed the space between them in a single step, took Cas in his hands, and kissed him.

Cas was hesitant at first, just like Dean had always thought he’d be the first time. But he quickly got the idea, and Dean gave a quiet, shuddering moan as Cas got more forceful with his lips and tongue, finally, _finally_ taking what he wanted.

**Notes for the Chapter:**

> My apologies to the prompter for deviating somewhat from their original prompt. I had to cut off the first part of the prompt due to character limit in the summary, but there was a line saying how Djinn have cousins that feed on fear, so maybe sirens have cousins that keep victims alive, etc. So I decided to use an incubus. I hope this isn't veering too far from what they wanted since "siren" was listed as the monster. Succubi are a canon creature in the spn universe, but have only ever been used in the comics. So I just went with what's known about them through the comics, and figured they probably are related, or at least similar enough to sirens that hopefully OP wouldn't mind the change. I just felt like what succubi/incubi do to/with their victims fit the fic the best. orz I hope it's okay.


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